Shotgun Desktop and Python 3

Hey all just need a little help. Per the latest release notes on shotgun desktop you can choose which python version to use by setting an env variable SHOTGUN_PYTHON_VERSION. Where can I integrate this so that by default shotgun desktop uses python2.7 creating an env variable is fine but I would rather this be set by default rather then having to go to each artists machine and manually create the variable. Where can I do this?

I’m pretty sure 2.7 is still the default and you have to opt in to python 3 with the environment variable.